In storage technology, use of mass data storage facilities to provide data storage as a backup to mitigate the impact of data loss is well known. In order to improve storage capacity, many different deduplication techniques have been developed in which duplicated data is removed and a pointer to previously stored data is stored in its place. One deduplication technique includes inline dedupe processing in which data is passed to a dedupe process which compares data items or blocks of data (such as files or parts of files) with existing stored data to remove duplications of data before it is passed to the backup storage. Another technique includes post dedupe processing in which data items are first stored and then deduplicated after the backup is complete.
Virtual Tape Libraries (VTL) are known to the inventors that use a virtualised tape access model such as, for example, Small Computer System Interface (SCSI), SCSI Stream Commands (SSC) specification. This assumes no random IO and will not allow a write to occur mid data stream without the truncation of later data in the stream (as per an actual tape device). As a result VTL does not enable easy access to stored data using existing file share systems, e.g. Network File System (NFS), Common Internet File System (CIFS), which are known Network Attached Storage (NAS) protocols allowing full random IO.